Another Lens question

Hello, I posted about 2 months ago, asking about what lens to buy as a general purpose (mostly landscape) lens for my Canon Rebel with a broken kit lens. I got a lot of advice and appreciate it. I went to various camera shops here in Toronto and was very disappointed by the help I didn't receive so went home. Ventured out again today with some more info. I have access as well to 2 full-body camera bodies (lingo may not be right) as well as my Rebel, so I would like a lens I can use on both cropped and full-body cameras. I didn't actually realize that lenses weren't always compatible with both... Now I am looking for recommendations for a 17-50'ish lens for now. Will add on with others later. Also, would anyone know anything about the L24-105 IS which is new in terms of whether it is good...thanks again.

Re: Another Lens question

... I have access as well to 2 full-body camera bodies (lingo may not be right)

full-frame? (i.e., the sensor is the same size as a frame of 135 format (35mm) film). The 5D/6D for Canons?

... so I would like a lens I can use on both cropped and full-body cameras. I didn't actually realize that lenses weren't always compatible with both...

Basically, you're looking for EF lenses, and avoiding EF-S lenses. EF lenses will mount and work on both kinds of bodies. However, because of the crop factor, if you stick only to full-frame lenses, you won't be able to go ultrawide. If you decide you need an ultrawide zoom, it might still be best to stick with an EF-S lens until/unless you move completely to full-frame.

Now I am looking for recommendations for a 17-50'ish lens for now.

The Canon EF 17-40 f/4L USM is probably the only under-$1k lens you can use on both a full frame and a crop. And it is NOT designed as a walkaround lens for a crop (although it can be used as one). It's designed to be an ultrawide lens on a full frame. There's also the EF 16-35 f/2.8L II USM, again, designed to be ultrawide on a crop body, but it's US$1400.

The Tamron 17-50/2.8 is for crop bodies only. The following nomenclature distinguishes crop vs. full-frame lenses:

Also, would anyone know anything about the L24-105 IS which is new in terms of whether it is good...thanks again.

The EF 24-105 f/4L IS USM is not a particularly new lens. It was introduced back in 2005, and it's the kit lens for Canon's full-frame cameras, which is why they are plentiful on the used market and cheap as L lenses go (very few Ls are <US$1k). The crop equivalent would be the EF-S 15-85 f/3.5-5.6 IS USM. I have a 24-105L on my 5DMkII, and love the hell out of it. It's a great walkaround/travel lens, but is a compromise in two main ways. The 24-105 zoom range is slightly larger than optimal, so you do give up some image quality, particularly at the wide end of the range, and it's an f/4 lens, which is a middling maximum aperture: neither particularly fast or slow. The IS can help you with lower-light photography handholding--but only if your subject is stationary.

The 24-70 f/2.8L II USM is probably a better lens for low light and portraits, because of the larger max. aperture, but it isn't stabilized. And the new lens (which many assume will become the kit lens for the 6D) is the EF 24-70 f/4L IS USM. It's mostly assumed to have better image quality than the 24-105 from the smaller range, but also be less expensive than the 24-70 f/2.8L II USM ($1300 vs. the 24-70/2.8 II's $2200 pricetag). Most folks, however, were hoping for the Mk II of the 24-70 to be an IS lens.

The reason the 24-something L lenses aren't necessarily ideal on crop body usage is because of the crop factor. 24mm gives a 38mm FoV equivalence on a crop body, which is more "widish" than "wide". Or, put another way, what you get with 24mm on a full frame body is what you'd get with a 15mm lens on a crop. As I said, going with only EF lenses tends to make it tougher to go wide on a crop body.

Re: Another Lens question

What Kathy wrote, +1.
Additional points:

1. Any of the three (four) the 24 to xx lenses will likely NOT be wide enough for you on your Rebel – that is a point you should consider.

2. The Canon EF-S Lenses will NOT MOUNT on a Canon “Full Frame” camera: the Tamron Di II, Sigma DC and Tokina DX will actually MOUNT and ‘work’ on your Canon EOS “Full Frame” Cameras – but they will vignette at some and maybe all, Focal Lengths.

This second point is most likely a minor consideration for you – but is worth mentioning in consideration of how often you might be using said “Full Frame” Cameras and for what uses.